Blizzard Warning Criteria

Just splitting off from the NOW thread...

In respect to the blizzard warning criteria, I think Oklahoma could pass for a bit less. That's an area of the country that typically doesn't get much snow, and when it does snow, I think it tends to shut everything down. As for MKX, they were reporting gusts over 35mph, but I'm not sure of the duration and haven't checked visibility.

Looking back in time, I don't think the Jan 1999 blizzard met criteria at my specific location here in Oakland county, as winds were barely making the 35mph mark. However, it *seemed* like a blizzard to many in the area because of the heavy snowfall rates (visibility under 1/4 mile for most of the event, with periods of blinding snow / thunder).

Rather than change the criteria, I think a better assessment of the situation needs to be made. If upstream and local METARs are reporting a solid 35knt wind gusts and analysis / models continue to show good wind and snow potential, then a blizzard warning would be more suitable.
 
Might be time for a new thread - but I wonder if we need to consider changing blizzard criteria. This storm did not meet criteria, and a quick check didn't find any sites in OK yesterday that met either...

All quiet around mid-Michigan, we picked up 1/4-1/2" ice with no major problems, roads were icy for a bit in the middle of the night but primarily just slush thanks to the very warm wx we've been having.

Not to drag this beyond a NOW thread, but I believe the NWS criteria for a blizzard is "where both the 10m wind speed is >=30kts and surface visibility is < 1/4 mile - in falling snow or ice pellets for at least three hours" (from the HPC website)". If that's the case, I can't imagine some places in northern OK didn't meet that yesterday (particularly the first half of the day). I know I saw numerous mesonet obs with gusts >40mph, and visibility in many places in the heavy snow bands was <1/4 mile. I suppose there may have been a problem with three continuous hours of those conditions given that the heavy snows were banded, but those conditions were at least off-and-on for more than a few hours.

Here in Edmond, OK, I'd estimate approx 5" of snow/sleet, though I haven't measured. Many of the nearby roads are slick, but certainly not impassable or terrible. I was a little disappointed that OUN didn't release as many LSRs for storm totals through the course of the events... I saw a dozen or so yesterday, but that pales in comparison to offices like EAX or SGF, which put out the same amount in about 2 hours, which made keeping track of snowfall totals much easier.
 
Yeah true enough Jeff...some NWS offices crank out the info and some just stay clammed up. A good tool now is the TV station blogs...this was pretty good information in most cases, especially the reports that were coming in where the thundersnow happened. But back to the thread...blizzards affect different areas in different ways. Out in Wyoming, these are probably about every other winter storm that comes along. In Oklahoma/S.Kansas like yesterday...the conditions got pretty wicked in those deep snow bands. Plus add in the flat land ares up there, the wind just roars across the barren wheat fields. I've driven through that area in a similar event and it was scary to come up on other cars appearing out of nowhere. Blizzard always conjurs up in non-met people's minds that the most horrific winter storm is in progress. Most people have NO idea what a blizzard is.
 
Blizzard always conjurs up in non-met people's minds that the most horrific winter storm is in progress. Most people have NO idea what a blizzard is.

That's the intention of a blizzard warning - it supposed to capture the public's attention and alert them to the fact that they shouldn't be driving unless there is an emergency. In the most severe blizzards, people are even advised to stay indoors (there are cases where people get disoriented and lost on their own property).
 
First - the official definition from NWS 10-513:

3.1 Blizzard. A blizzard means that the following conditions are expected to prevail for a
period of 3 hours or longer:
a. Sustained wind or frequent gusts to 35 miles an hour or greater; and
b. Considerable falling and/or blowing snow (i.e., frequently reducing visibility below
1/4 mile).
Although there is no set temperature requirement for blizzard conditions, the life-threatening
nature of the low temperatures in combination with the other hazardous conditions of wind,​
snow, and poor visibility increases dramatically when the temperature falls below 20*F.



The public refers to any big winter storm as a blizzard... Blizzard warnings are RARELY (if ever) successfully warned in advance, because the criteria are incredibly hard to meet let alone forecast. They usually are issued during an event when mets see the numbers start to go up - but by then, everybody knows about it, they are already indoors unless they have to go out, and if they have to go out - it doesn't matter!

So would relaxing the criteria (not sustained for 3 hours, or maybe not so tight on vis since we're relying on all automated vis sensors these days) be a service to the public?
 
NWS guidelines also say this...

During early and late season storms, or in places where winter weather is rare, WFOs may issue winter weather warnings based on significant public impact events which do not meet local warning criteria. For example, if a storm (such as one with heavy, wet snow or a mixture of snow, freezing rain and sleet) is forecast to significantly affect transportation, commerce or electrical power service, then the event warrants a warning.

...and in many cases the need to get a message out will outweigh the sometimes arbitrary guidelines. In the case of the Oklahoma blizzard warnings, criteria was likely met in several locations for short periods of time. However, the desired effect of the message was to get people's attention and to alert them that a potentially life-threatening event was underway.

I can tell you from first hand experience that you can have treacherous, dangerous driving conditions even if the winds are only gusting to 30 MPH.

Rick
 
Yeah I was a bit perturbed too at the lack of real-time reports from OUN yesterday. I'm sure that most people have far too much going on to bother yadda yadda - but it seems like in events past there was an overabundance of reports of "such-and-such-a-place has received .15" of ice so far.......". Last night - during the first REAL event in a while - there was nothing. Just a Graphicast image of the "expected" accumulations over the next 24 hours.

I was also interested - on my side of the fence - to watch and see how LZK attempted to forecast the cold air moving down behind the front. I think their forecasts would have panned out if it had not been for the pesky low that developed along the front by mid-afternoon slap-bang in the middle of southern Arkansas. This meant that areas in southeast Tejas froze before Conway and LZK did......pretty pathetic! I can only assume that this was due to a combination of the low south-east of us which kept us bathed in the (comparatively) tropical conditions of some wrap-around heat and moisture, and the wafer-thin layer of cold air that was trying to trundle up and down the Ozarks towards us........poor cold air. It must be knackered.

KL
 
The public refers to any big winter storm as a blizzard... Blizzard warnings are RARELY (if ever) successfully warned in advance, because the criteria are incredibly hard to meet let alone forecast. They usually are issued during an event when mets see the numbers start to go up - but by then, everybody knows about it, they are already indoors unless they have to go out, and if they have to go out - it doesn't matter!

So would relaxing the criteria (not sustained for 3 hours, or maybe not so tight on vis since we're relying on all automated vis sensors these days) be a service to the public?

I think a better method of awareness would be to use blizzard watches for events that appear as though they could meet the criteria. For example, if the event is 12 - 18 hours away and there is good agreement that there will be a combination of high wind in excess of 35knts and heavy snow, then that might be a good flag for blizzard watches.

I think the public perceives a blizzard to be worse than "a major winter storm". The watches would alert the public and leave a bit more confidence on the forcasters plate. Of course, they would still need to be used sparingly or the watches/warnings would end up much like SVR watches/warnings.
 
WFOs may issue winter weather warnings based on significant public impact events which do not meet local warning criteria.

Agreed - but that does not apply to blizzards. That refers to issuing a Winter Storm Warning instead of an Advisory - it does not allow for reduction of the blizzard criteria.
 
I think a better method of awareness would be to use blizzard watches for events that appear as though they could meet the criteria.

That is what is used today...

Blizzard Watch - Conditions are favorable for a blizzard event to meet or​
exceed Blizzard Warning criteria in the next 12 to 48 hours.

What I'm saying is that it is VERY difficult to forecast that winds will be > 35mph for 3 hours AND at the same time reducing vis to 1/4mi or less. Very. Look how bad some forecasters did with basic snowfall in this past storm, and now you throw in 24 hours advance worth of pinning down where the isolated extreme snow will happen. Can't do it...
 
Rob,

I'm not sure I understand. Are you saying the criteria should be lowered? Or are you for a higher criteria?

I know high wind watches and warnings are issued with a fair amount of accuracy. If you have a potential for heavy snow and you also meet high wind watch criteria, then I would say a blizzard watch would be a good option. The quarter-mile visibility is a result of the wind + snow, so that would be your forecast starting point.

Even with the NWS "having" blizzard watches available, they aren't used much outside of Alaska. Even last year's Northern Plains blizzard was "missed" by a blizzard watch; models consistently predicted +45knt surface winds and very heavy QPF in 20F temps. Why no blizzard watch? It was quite obvious that those conditions could be met.

With that said, the prediction would still be difficult for marginal events. If the NAM is showing only 35knts at one timestep, then what? Winter storm watch, or blizzard watch? Most of the events we see across continental US would be "marginal", so I guess there really is no benefit ;-)
 
Lowered... Unless someone found a hidden spot - none of the blizzard warnings with this storm , issued in WI & OK, verified with the current criteria.
 
They could always go with a blizzard warning for slightly lowered thresholds like some of you guys have suggested above; and to keep the "mystique" of a really bad storm that rarely happens (like the current blizzard threshold has) go with a super blizzard warning for REALLY bad blizzards.

Something like this..
For a blizzard warning: winds of 25mph sustained or frequent gusts above 30mph, combined with heavy snow with visibilities <3/8 mile for 3hrs consectutively, or numerous periods within 6hrs.

For a super blizzard warning: winds of 35mph sustained or frequent gusts above 45mph, combined with heavy snow and visibilities at or <1/4 mile for a minimum of 3hrs.
 
Lowered... Unless someone found a hidden spot - none of the blizzard warnings with this storm , issued in WI & OK, verified with the current criteria.

I disagree, Rob. Below are the Enid obs. The area of north central Oklahoma certainly saw frequent gusts at or above 35 mph for most of the day on the 30th. Even though the visibility is only reported as "only" 1/4SM... ASOS and AWOS sensors rarely report "M1/4 SM". These obs from 15z to 21z would verify 6-hour blizzard, based solely on the current criteria. Perhaps Rick Smith can jump in on this... but the observations, to me, would support at least a 6-hr blizzard for parts of NC Oklahoma per NWS definition. I've done a lot of blizzard researching for western Kansas since I moved down here... and the Visibility reported by automated stations are usually not low enough from my experience, in very strong wind+snow situations out on the high plains. [SIZE=-1]

METAR KWDG 301455Z 33025G35KT 1/4SM SN BLSN VV001 M08/M09 A3017
METAR KWDG 301550Z 34020G32KT 1/4SM SN BLSN VV001 M08/M09 A3019
METAR KWDG 301650Z 33020G30KT 1/4SM SN BLSN VV001 M08/M09 A3015
METAR KWDG 301750Z 34020G32KT 1/4SM SN BLSN VV002 M08/M09 A3015
METAR KWDG 301850Z 33022G36KT 1/4SM SN BLSN VV001 M08/M09 A3017
METAR KWDG 301950Z 33020G29KT 1/4SM SN BLSN VV002 M08/M09 A3010
METAR KWDG 302050Z 33020G31KT 1/4SM SN BLSN VV002 M07/M09 A3007[/SIZE]
Mike U
 
While it's nice to 'infer' that vis was < 1/4mi, and I don't disagree with that, the fact remains that the observations don't meet current criteria...
 
I think I'll chime in here just a bit. I'm not a scientist, but I DO report weather to the General Public. From about 5:00 p.m. to about 8:30 p.m. I was all over Kay County Oklahoma. From early afternoon to after the time I finally got home, we had steady winds of 35 mph with gusts to 40+. Ground visibility was 1/4 mile to 1/2 mile depending on the wind and what was breaking the wind. Blowing snow was the rule. Driving conditions were treacherous at best. From my observations at several points in Kay County, we met the published criteria for a blizzard warning for at least 3/4 of each hour it was in effect.

I also know that the Warning got our attention. We made a concerted effort to get this message out to the public, where as we probably wouldn't have pushed as hard for a Winter Storm Warning or Heavy Snow Warning.

I'm only guessing, but I would bet this was the effect the Warning Coordinator wanted. The Met's at OUN knew what was coming and wanted to make sure the word got out as effectively as possible. With our station, they achieved that goal.

One can argue over the letter of the law all day. However, the word got out and it was generally effective with the exception of the Ponca City Schools. I will be addressing that issue with the Schools on a different tack and not on this forum.

Just my small and un-informed opinion.

John Diel
 
While it's nice to 'infer' that vis was < 1/4mi, and I don't disagree with that, the fact remains that the observations don't meet current criteria...

But it's also not just automated surface observations... when it comes to warning decision making like this, first-hand reports have a huge weight in determining what's really going on. When deputies out on the roads are reporting that they can't see about 50 feet in front of them, yet the nearby ASOS ob says "1/4 SM".. and you get a lot of these 50-100 feet visibility reports with 35mph winds and SN or +SN... and if that is ocurring or is expected to occur for 3 hours or more, then that's the NWS definition of a blizzard. We can't just rely on ASOS/AWOS obs, they are only one part of the whole warning and verification process. But I think I'm preaching to the choir, here..
 
Mike raises a good point - looking at only automated surface observations will not always give you an accurate picture of what happened. NWS relies very heavily on human observations to help fill in the gaps, whether we're dealing with winter storms, or convection, or flooding, or high wind events, etc. After all, it is the human that we're issuing the warning for, not a piece of equipment. A report like the one John provides is verification that we had blizzard conditions.

Definitions and guidelines are great, but service and getting the appropriate message out during a critical situation is much more important.

Rick
 
Definitions and guidelines are great, but service and getting the appropriate message out during a critical situation is much more important.

I completely agree, although John's observations do not hit criteria either (no < 1/4mi vis reported.) So if we keep 'bending' the criteria to issue warnings -- wouldn't it make sense to change the criteria so everybody is in sync?

I'm curious - did the warning go anywhere outside of your CWA? If not, is it safe to assume that the other office(s) did not want to "bend" the criteria as much, and there's nothing that causes the public more confusion than a Winter Storm Warning on one side, Heavy Snow Warning on another and a Blizzard Warning to your west. That's why I don't relay any winter weather headlines other than that with the word blizzard - it's just too much to spell out.

But that's yet another topic split ;>

- Rob
 
Rdale,
Yes, the warning did go over into Tulsa CWA (Osage, Washington and I believe Nowata counties, plus counties in Kansas) and was extended beyond the 9:00 p.m. expiration that Norman had. Maybe I didn't make myself very clear (Duh!). The visibilities on the major roadways in Kay County were less than 1/4 mile most of the time. Not all the time, but most of it. I gaged my visibility on when I could see oncoming traffic and when I could see street lights when available. I did not gage my visibility on the snow reflecting from my headlights. Though that was a BIG factor in my reporting condition to the General Public and made a VERY big difference in travel.

When the immediate visibilities are nil (blowing snow reflecting from headlights and you can't see the sides of the road because of it) but you can see the oncoming traffic headlights 2 or 3 tenths of a mile, it's a tough call. I would also gage my visibility on the vehicle in front of me when available by viewing when I could see the tail lights and when I couldn't.
 
Northern Oklahoma

I was out in the storm on Thursday reporting conditions. Having grown up on Michigan, Grand Rapids I have experienced heavy snow and blizzard conditions. In the 25 years I have lived in Tulsa I have not seen it come close to what a true blizzard is. However I was on Hwy 169 in Nowata County, and had sustained visability of under 1/4 mile with heavy snow and blowing and drifting occuring. Many roads were impassable. Had I not been driving an AWD Subaru it would have been real ugly.

I do believe that near the Kansas state line the blizzard conditions were met. I also feel the warning helped keep people off the road since there was very few people out at all.
 
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